During undergrad, I worked with permanent magnets in a plasma physics laboratory, mostly using them to build instrumentation to accelerate gas plasma plumes for spectrographic analysis. This sounds neat in principle, but I'm skeptical of any meaningful application. Dealing with permanent magnets of any meaningful size (let alone arrays of them the size of which would be required) becomes extremely dangerous, and requires a lot of care and attention to detail. Especially considering some of the progress in lowering the cost of high-temperature superconducting magnets, this might be a tough sell. I'm curious if there are any statistics for accident rates of magnets vs. cryogens like liquid nitrogen in development environments.